An oxide thin film transistor (TFT) array substrate includes a TFT array substrate of a back channel etching type, a TFT array substrate of a coplanar type, a TFT array substrate of an etching barrier type, and so on. The TFT array substrate of the back channel etching type and the TFT array substrate of the coplanar type are widely used because of their simple structures.
The TFT array substrate of the back channel etching type has a structure in which a gate electrode, a gate insulating layer, an oxide active layer, a source electrode, a drain electrode, a passivation layer, and a pixel electrode are sequentially formed on a base substrate. During forming the source electrode and the drain electrode, a source/drain layer is firstly deposited on the oxide active layer, and then the source electrode and the drain electrode are formed by a single patterning process.
The TFT array substrate of the coplanar type has a structure in which the gate electrode, the gate insulating layer, the source electrode, the drain electrode, the oxide active layer, the passivation layer and the pixel electrode are sequentially formed on the base substrate. During forming the oxide active layer, a metal oxide layer is firstly deposited on the source electrode, the gate insulating layer and the drain electrode, and the oxide active layer is formed by a single patterning process.